Introduction trigonometry 
Hughes, Isabella 
 - USA: Willford Press  2020 
 - viii, 220p. ; 25.4cm. 
<br/><br/> includes references index 
<br/><br/><label>ISBN: </label>9781682858738 
<br/><br/><label>Dewey Class. No.: </label>C 516 .24 H893 2020